Downwell system with swellable packer including blowing agent

Abstract

A downwell packer assembly includes a tubular member and a packer element mounted on the tubular member. The packer element comprises a composition that includes a polymer. The packer element includes micropores (typically created via a blowing agent). When the packer element is exposed to a swelling fluid, such as water or hydrocarbon, the micropores can help to control and, in some instances, increase the rate of swelling. Such swelling enables the packer element to form a seal against the walls of the wellbore.

1 . A composition suitable for use in a packer element for a wellbore, comprising:
 a swellable polymer; and   a blowing agent.   
     
     
         2 . The composition defined in  claim 1 , wherein the swellable polymer is a water-swellable polymer. 
     
     
         3 . The composition defined in  claim 2 , wherein the water-swellable polymer is selected from the group consisting of: starch-polyacrylate acid graft copolymers; polyvinyl alcohol cyclic acid anhydride graft copolymers; isobutylene maleic anhydride; acrylic acid type polymers, vinylacetate-acrylate copolymers; polyethylene oxide polymers; carboxymethyl cellulose type polymers; and starch-polyacrylonitrile graft copolymers. 
     
     
         4 . The composition defined in  claim 2 , wherein the blowing agent is a water-activated blowing agent. 
     
     
         5 . The composition defined in  claim 4 , wherein the blowing agent is selected from the group consisting of: NaHCO3 and 4,4′-oxy-bis(benzenesulfohydrazide). 
     
     
         6 . The composition defined in  claim 1 , wherein the swellable polymer is a hydrocarbon-swellable polymer. 
     
     
         7 . The composition defined in  claim 6 , wherein the hydrocarbon-swellable polymer is selected from the group consisting of: ethylene propylene rubber, ethylene-propylene-diene terpolymer rubber, butadiene rubber, brominated butadiene rubber, chlorinated butadiene rubber, chlorinated polyethylene, neoprene rubber, styrene butadiene copolymer rubber, sulphonated polyethylene, ethylene acrylate rubber, epichlorohydrin ethylene oxide copolymer, silicone rubbers and fluorsilicone rubber. 
     
     
         8 . The composition defined in  claim 1 , wherein the composition includes micropores. 
     
     
         9 . The composition defined in  claim 1 , wherein the blowing agent is present in the swellable polymer in an amount of about 0.1 to 4 percent by weight. 
     
     
         10 . A packer assembly, comprising:
 a tubular member; and   a packer element mounted on the tubular member, the packer element comprising a composition that includes a polymer, the packer element including micropores.   
     
     
         11 . The packer assembly defined in  claim 10 , wherein the polymer is a swellable polymer. 
     
     
         12 . The packer assembly defined in  claim 11 , wherein the swellable polymer is a water-swellable polymer. 
     
     
         13 . The packer assembly defined in  claim 12 , wherein the water-swellable polymer is selected from the group consisting of: starch-polyacrylate acid graft copolymers; polyvinyl alcohol cyclic acid anhydride graft copolymers; isobutylene maleic anhydride; acrylic acid type polymers, vinylacetate-acrylate copolymers; polyethylene oxide polymers; carboxymethyl cellulose type polymers; and starch-polyacrylonitrile graft copolymers. 
     
     
         14 . The packer assembly defined in  claim 10 , wherein the composition further comprises a blowing agent. 
     
     
         15 . The packer assembly defined in  claim 14 , wherein the blowing agent is a water-activated blowing agent. 
     
     
         16 . The packer assembly defined in  claim 14 , wherein the blowing agent is present in the swellable polymer in an amount of about 0.1 to 4 percent by weight. 
     
     
         17 . The packer assembly defined in  claim 14 , wherein the blowing agent is selected from the group consisting of: NaHCO3 and 4,4′-oxy-bis(benzenesulfohydrazide). 
     
     
         18 . The packer assembly defined in  claim 11 , wherein the swellable polymer is a hydrocarbon-swellable polymer. 
     
     
         19 . The packer assembly defined in  claim 18 , wherein the hydrocarbon-swellable polymer is selected from the group consisting of: ethylene propylene rubber, ethylene-propylene-diene terpolymer rubber, butadiene rubber, brominated butadiene rubber, chlorinated butadiene rubber, chlorinated polyethylene, neoprene rubber, styrene butadiene copolymer rubber, sulphonated polyethylene, ethylene acrylate rubber, epichlorohydrin ethylene oxide copolymer, silicone rubbers and fluorsilicone rubber. 
     
     
         20 . The packer assembly defined in  claim 10 , wherein the micropores are formed during vulcanization. 
     
     
         21 . A packer assembly, comprising:
 a tubular member; and   a packer element mounted on the tubular member, the packer element comprising a composition that includes a swellable polymer, the packer element including micropores formed by a blowing agent.